Wouldn't that be the throw out bearing? (My technical terminology is severely lacking in the transmission dept.)
So the a throw out bearing would only make noise when the clutch is depressed. This bearing is part of the clutch assembly.
However the input shaft bearing is deep in the transmission and will make noise when ever the car is gear and noise will stop when the engine is not in connection with the transmission. I think this is fairly rare and at the atleast I haven’t heard the issues with ours car, if it just that a new transmission would be only reasonable option as labour hours would be tremendous.
But I don’t think it’s that I’m not expert but, u should always be able to hear it if it was the input shaft bearing not just in a garage it would be very pronounced like a spun rod but quiter.
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